P- element Induced Wimpy Testis (PIWI), a Novel Powerful Candidate Diagnostic Marker for Hepatocellular Carcinoma

Abstract P-Element-induced wimpy testis (PIWI) proteins are engaged in epigenetic regulation of gene expression in germline cells when they are in combination with PIWI-interacting RNA (piRNA). Different types of tumour cells have been found to exhibit abnormal expression of piRNA and PIWI proteins. HCC is majorly diagnosed in later stages, which is associated with lower survival rates. There is an urgent need for improved, more specific and less invasive diagnostic methods that can detect earlier stages of the disease. Purpose: The aim of this study was to assess the diagnostic potential by determining the expression profiles of PIWI-like protein-1, -2, -3, & -4 (PIWIL1, PIWIL2, PIWIL3, & PIWIL4) in hepatocellular carcinoma, and determine its association with clinicopathological features. Methods: Samples from patients comprising serum and frozen fragments of paired tissue specimens (tumour and adjacent non-malignant liver tissue) were employed for molecular analyses. Real-time polymerase chain reaction was performed on 50 tissue and serum samples from HCC patients and 25 serum samples from healthy controls. Results: The PIWIL1, PIWIL2, PIWIL3, & PIWIL4 levels were significantly (<0.001) higher in both HCC tissue and serum samples than in the controls. Additionally, the diagnostic performance was assessed by ROC curves, the PIWIL1-4 levels in serum showed better potential and sensitivity to screen HCC patients than their levels in tissues. Moreover, some PIWIL elements were found here to be significantly correlated with the HCC profile. Conclusion: PIWI expression is considered as a powerful non-invasive diagnostic tool for HCC. Our findings also support the theory that PIWIL expression is critical for cancer progression.